I think chain cleaning technique & practices is partly a function of how you use your bike. As a commuter, I clean my chain once a week and wipe it down any day it rains. If it does develop visible rust, such as if I forgot to wipe it down on a rainy day or if there's snow, ice & salt, I take the Simple Green to it and use the chain cleaner tool. Otherwise, I just run it through a rag.

I am not so patient as to wait until it is completely not black. That takes forever, and a few applications of oil. Yeah, I guess the purpose of the lube is to clean the chain more than it is to lube moving parts. It took me a while to figure that out. Leaving oil on the chain just gives the dirt something to stick to.

I replace my chain every 1500 miles. At the bike shop we check it with the tool and it's approaching 1/8 inch at that point. I was so proud of myself because my cassette lasted 5000 miles, and the mechanic said that was due to my diligent chain cleaning!